I have the DVB drivers loaded. Now how can I test it?

How do I tune my TV-channels? Where do I get the frequencies from?

Try the scan command as described above or on the page of its package LinuxTV dvb-apps.

How many devices are supported in a system?

In respect to DVB devices, see this thread. There is also a patch that has been submitted that will allow one to configure the max adapters defined.
In respect to analog devices, see this thread.

Udev can be used to maintain a persistent order. MythTv has extensive information on this. The simplest way is to use the adapter_nr option available for most top level DVB modules.

Troubleshooting

Under Ubuntu (I assume that this also applies to other linux systems), make sure that the user is in the video group in /etc/group.

Any software I use comes up with error messages like "can't find demux".

This means that /dev/dvb/adapter0/demux is missing. Probably your card drivers are not installed properly. Then, you don't have anything in /dev/dvb/. If that's the case, make sure above that you have all in your kernel config (of your running kernel, of course) and that you loaded them all with modprobe.

My device was working perfectly, but now it is not recognized anymore. What is the problem?

It's possible that you're using a different kernel now, so you have to install the driver again and ensure that the firmware is reached by the hotplug system.

My DVB device is recognized but I'm not able to use it. What can I do?

You should check that the /dev/dvb exists and that you have the correct permissions to read and write that directory.

Hardware compatibility issues

Some motherboard chipsets are known for hardware incompatibilities with several PCI cards. Depending on motherboard chipset, BIOS, driver versions and connected PCI cards, it could be necessary to change the PCI latency of the DVB card or the latency value of other PCI cards. Acoustic and image interferences can appear after 10 to 30 minutes playback. Kernel error messages like "timed out waiting for end of xfer" can occure in /var/log/syslog when the PCI latency is too low. But there are also acoustic and image interferences possible when the PCI latency is too high. The current PCI latency can be shown via command "lspci -v". The PCI latency value can be set via command setpci (see manual page of setpci, example: setpci -v -s 03:06.0 latency_timer=96 ). The appropriate value depends on the specific hardware configuration. Play around with the value and restart DVB playback. Otherwise, you can try to swap PCI cards or a different motherboard with a different chipset.

S-Video input in black and white

When you are watching the signal coming through the S-Video input of your card, the picture is in black and white, that even when the source is in colour. This is basically what will append when you are connecting a composite source to a S-Video input. They are relatively expensive box to deal with this on the market, but it is an alternative solution that will work well in most cases. See Composite to S-Video.